The use of printing presses and rotary die cutters are well known. These systems can perform several functions in addition to printing and cutting, such as error detection, registration control and splicing. Often, these functions have to be performed manually, which can result in low product quality and lost time during manufacturing. Thus, the use of automation in printing and cutting can be highly desirable to improve product quality and manufacturing efficiency, such as tracking accepted and rejected product.
Both manual and automatic methods have been used to inspect a product printed on a web of material. In a prior method of manual inspection, an operator visually inspected the web and physically flagged the defects while the web was being printed. Later, the flagged location on the web was manually relocated and the defective product removed. This manual method is overly time consuming.
In a prior method of automatic web inspection, a digital area array camera captured a shot of a large part of a web having a printed product and compared the digital image to a perfect or "golden" image of the product. This method, however, can use too much computer memory if a large image is captured. One solution to this problem has been to reduce the resolution of the captured image. This reduction in resolution, however, reduces the effectiveness of the system by allowing larger defects to go through undetected.
Other printing and cutting systems have attempted to effectively track defects in a material. U.S. Pat. No. 4,951,223 to Wales et al. discloses a web material inspection system for recording and storing an image of the web material and for reviewing the web image and detecting defects in the web. The Wales et al. apparatus can use a digital memory device to store the web image. Disadvantageously, the Wales et al. apparatus does not use a computer or network to track the web defects.
The use of identification codes during manufacturing is also known in the art. U.S. Pat. No. 4,830,380 to Six discloses a printed material bearing an identifying code for keeping track of a large number of non-identical printed patterns. The identifying code is printed on the sheet for each pattern and identifies which pattern it is. U.S. Pat. No. 4,374,451 to Miller discloses a method of assembling a CRT using a coded part that remains with the CRT during its assembly and further using a computer network to track the CRT through its manufacturing process. Disadvantageously, neither the Six apparatus nor the Miller method are capable of detecting errors.
The use of apparatus for maintaining the proper registration of printed and cut materials is also known in the art. U.S. Pat. No. 5,383,392 to Kowalewski et al. discloses a sheet registration control for adjusting the registration of a sheet as it passes from a printing section to a die-cutting section. To accomplish this, Kowalewski et al. discloses that placed between these two sections is a transfer section which uses computers to determine the registration of the sheet and to determine whether or not the sheet should be sped up or slowed down to bring the sheet in proper registration for the die-cutting section. Disadvantageously, the Kowalewski et al. apparatus does not disclose the tracking of the product from their rolls or the tracking of errors.
U.S. Pat. No. 4,177,730 to Schriber et al. discloses a method and apparatus for web printing that uses markings and scales to establish a reference position to which the rotatable members of the press are adjusted with respect to. The Schriber et al. apparatus, however, does not disclose the computer control or adjustment of the web press.
Apparatus for splicing a new roll to an old one is also known in the art. U.S. Pat. No. 5,464,289 to Beaudry et al. discloses an electrographic label printing system that includes an automatic shutoff roller and splicer for stopping the printing process and splicing a new roll of stock onto the old roll without rethreading the system.
None of the above systems, however, take advantage of computer networking to accomplish several of necessary monitoring and controlling functions of a printing press and die cutter in real-time, such as tracking the product defects and accumulating information about the defects throughout the manufacturing process.
What is desired, therefore, is an on-line computer controlled system for precisely detecting and tracking errors for a specific web roll in real-time for printing press and die cutting manufacturing system. Additionally, other printing and die cutting functions are desired to be accomplished in real-time through computer control, such as monitoring die cutting registration and detecting web splices.